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Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter. Such “defence portfolios” that defend prey against a single instance of predation are distributed across and within successive stages of the predation sequence (encounter, detection, identification, approach (attack), subjugation and consumption). We contend that at present, our understanding of defence portfolio evolution is incomplete, and seen from the fragmentary perspective of specific sensory systems (e.g., visual) or specific types of defences (especially aposematism). In this review, we aim to build a comprehensive framework for conceptualizing the evolution of multiple prey defences, beginning with hypotheses for the evolution of multiple defences in general, and defence portfolios in particular. We then examine idealized models of resource trade-offs and functional interactions between traits, along with evidence supporting them. We find that defence portfolios are constrained by resource allocation to other aspects of life history, as well as functional incompatibilities between different defences. We also find that selection is likely to favour combinations of defences that have synergistic effects on predator behaviour and prey survival. Next, we examine specific aspects of prey ecology, genetics and development, and predator cognition that modify the predictions of current hypotheses or introduce competing hypotheses. We outline schema for gathering data on the distribution of prey defences across species and geography, determining how multiple defences are produced, and testing the proximate mechanisms by which multiple prey defences impact predator behaviour. Adopting these approaches will strengthen our understanding of multiple defensive strateg

Prey seldom rely on a single type of antipredator defence, often using multiple defences to avoid predation. In many cases, selection in different contexts may favour the evolution of multiple defences in a prey. However, a prey may use multiple defences to protect itself during a single predator encounter. Such “defence portfolios” that defend prey against a single instance of predation are distributed across and within successive stages of the predation sequence (encounter, detection, identification, approach (attack), subjugation and consumption). We contend that at present, our understanding of defence portfolio evolution is incomplete, and seen from the fragmentary perspective of specific sensory systems (e.g., visual) or specific types of defences (especially aposematism). In this review, we aim to build a comprehensive framework for conceptualizing the evolution of multiple prey defences, beginning with hypotheses for the evolution of multiple defences in general, and defence portfolios in particular. We then examine idealized models of resource trade-offs and functional interactions between traits, along with evidence supporting them. We find that defence portfolios are constrained by resource allocation to other aspects of life history, as well as functional incompatibilities between different defences. We also find that selection is likely to favour combinations of defences that have synergistic effects on predator behaviour and prey survival. Next, we examine specific aspects of prey ecology, genetics and development, and predator cognition that modify the predictions of current hypotheses or introduce competing hypotheses. We outline schema for gathering data on the distribution of prey defences across species and geography, determining how multiple defences are produced, and testing the proximate mechanisms by which multiple prey defences impact predator behaviour. Adopting these approaches will strengthen our understanding of multiple defensive strateg

Trait databases have become important resources for large-scale comparative studies in ecology and evolution. Here we introduce the AnimalTraits database, a curated database of body mass, metabolic rate and brain size, in standardised units, for terrestrial animals. The database has broad taxonomic breadth, including tetrapods, arthropods, molluscs and annelids from almost 2000 species and 1000 genera. All data recorded in the database are sourced from their original empirical publication, and the original metrics and measurements are included with each record. This allows for subsequent data transformations as required. We have included rich metadata to allow users to flter the dataset. The additional R scripts we provide will assist researchers with aggregating standardised observations into species-level trait values. Our goals are to provide this resource without restrictions, to keep the AnimalTraits database current, and to grow the number of relevant traits in the future.

Trait databases have become important resources for large-scale comparative studies in ecology and evolution. Here we introduce the AnimalTraits database, a curated database of body mass, metabolic rate and brain size, in standardised units, for terrestrial animals. The database has broad taxonomic breadth, including tetrapods, arthropods, molluscs and annelids from almost 2000 species and 1000 genera. All data recorded in the database are sourced from their original empirical publication, and the original metrics and measurements are included with each record. This allows for subsequent data transformations as required. We have included rich metadata to allow users to flter the dataset. The additional R scripts we provide will assist researchers with aggregating standardised observations into species-level trait values. Our goals are to provide this resource without restrictions, to keep the AnimalTraits database current, and to grow the number of relevant traits in the future.

Trait databases have become important resources for large-scale comparative studies in ecology and evolution. Here we introduce the AnimalTraits database, a curated database of body mass, metabolic rate and brain size, in standardised units, for terrestrial animals. The database has broad taxonomic breadth, including tetrapods, arthropods, molluscs and annelids from almost 2000 species and 1000 genera. All data recorded in the database are sourced from their original empirical publication, and the original metrics and measurements are included with each record. This allows for subsequent data transformations as required. We have included rich metadata to allow users to flter the dataset. The additional R scripts we provide will assist researchers with aggregating standardised observations into species-level trait values. Our goals are to provide this resource without restrictions, to keep the AnimalTraits database current, and to grow the number of relevant traits in the future.

A prominent question in animal research is how the evolution of morphology and ecology interacts in the generation of phenotypic diversity. Spiders are some of the most abundant arthropod predators in terrestrial ecosystems and exhibit a diversity of foraging styles. It remains unclear how spider body size and proportions relate to foraging style, and if the use of webs as prey capture devices correlates with changes in body characteristics. Here, we present the most extensive data set to date of morphometric and ecological traits in spiders. We used this data set to estimate the change in spider body sizes and shapes over deep time and to test if and how spider phenotypes are correlated with their behavioral ecology. We found that phylogenetic variation of most traits best fitted an Ornstein–Uhlenbeck model, which is a model of stabilizing selection. A prominent exception was body length, whose evolutionary dynamics were best explained with a Brownian Motion (free trait diffusion) model. This was most expressed in the araneoid clade (ecribellate orb-weaving spiders and allies) that showed bimodal trends toward either miniaturization or gigantism. Only few traits differed significantly between ecological guilds, most prominently leg length and thickness, and although a multivariate framework found general differences in traits among ecological guilds, it was not possible to unequivocally associate a set of morphometric traits with the relative ecological mode. Long, thin legs have often evolved with aerial webs and a hanging (suspended) locomotion style, but this trend is not general. Eye size and fang length did not differ between ecological guilds, rejecting the hypothesis that webs reduce the need for visual cue recognition and prey immobilization. For the inference of the ecology of species with unknown behaviors, we propose not to use morphometric traits, but rather consult (micro-)morphological characters, such as the presence of certain podal structures. Thes

Do animals set the course for the evolution of their lineage when manipulating their environment? This heavily disputed question is empirically unexplored but critical to interpret phenotypic diversity. Here, we tested whether the macroevolutionary rates of body morphology correlate with the use of built artifacts in a megadiverse clade comprising builders and nonbuilders—spiders. By separating the inferred building-dependent rates from background effects, we found that variation in the evolution of morphology is poorly explained by artifact use. Thus natural selection acting directly on body morphology rather than indirectly via construction behavior is the dominant driver of phenotypic diversity.

Contains fulltext : 216783.pdf (publisher's version ) (Closed access)

Contains fulltext : 216783.pdf (publisher's version ) (Closed access)

Contains fulltext : 216783.pdf (publisher's version ) (Closed access)

A main goal of ecological and evolutionary biology is understanding and predicting interactions between populations and both abiotic and biotic environments, the spatial and temporal variation of these interactions, and the effects on population dynamics and performance. Trait-based approaches can help to model these interactions and generate a comprehensive understanding of ecosystem functioning. A central tool is the collation of databases that include species trait information. Such centralized databases have been set up for a number of organismal groups but is lacking for one of the most important groups of predators in terrestrial ecosystems – spiders. Here we promote the collation of an open spider traits database, integrated into the global Open Traits Network. We explore the current collation of spider data and cover the logistics of setting up a global database, including which traits to include, the source of data, how to input data, database governance, geographic cover, accessibility, quality control and how to make the database sustainable long-term. Finally, we explore the scope of research questions that could be investigated using a global spider traits database.

The evolution of a visual signal will be affected by signaller and receiver behaviour, and by the physical properties of the environment where the signal is displayed. Crab spiders are typical sit-and-wait predators found in diverse ambush sites, such as tree bark, foliage and flowers. Some of the flower-dweller species present a UV+-white visual lure that makes them conspicuous and attractive to their prey. We hypothesised that UV+-white colouration was associated with the evolution of a flower-dwelling habit. In addition, following up on results from a previous study we tested whether the UV+-white colouration evolved predominantly in flower-dwelling species occurring in Australia. We measured the reflectance of 1149 specimens from 66 species collected in Australia and Europe, reconstructed a crab spider phylogeny, and applied phylogenetic comparative methods to test our hypotheses. We found that the flower-dwelling habit evolved independently multiple times, and that this trait was correlated with the evolution of the UV+-white colouration. However, outside Australia non-flower-dwelling crab spiders also express a UV+-white colouration. Therefore, UV+-white reflectance is probably a recurring adaptation of some flower-dwellers for attracting pollinators, although it may have other functions in non-flower-dwellers, such as camouflage.

The evolution of a visual signal will be affected by signaler and receiver behavior, and by the physical properties of the environment where the signal is displayed. Crab spiders are typical sit-and-wait predators found in diverse ambush sites, such as tree bark, foliage, and flowers. Some of the flower-dweller species present a UV-white visual lure that makes them conspicuous and attractive to their prey. We hypothesized that UV-white coloration was associated with the evolution of a flower-dwelling habit. In addition, following up on results from a previous study we tested whether the UV-white coloration evolved predominantly in flower-dwelling species occurring in Australia. We measured the reflectance of 1149 specimens from 66 species collected in Australia and Europe, reconstructed a crab spider phylogeny, and applied phylogenetic comparative methods to test our hypotheses. We found that the flower-dwelling habit evolved independently multiple times, and that this trait was correlated with the evolution of the UV-white coloration. However, outside Australia non-flower-dwelling crab spiders also express a UV-white coloration. Therefore, UV-white reflectance is probably a recurring adaptation of some flower dwellers for attracting pollinators, although it may have other functions in non-flower dwellers, such as camouflage.

The world in color presents a dazzling dimension of phenotypic variation. Biological interest in this variation has burgeoned, due to both increased means for quantifying spectral information and heightened appreciation for how animals view the world differently than humans. Effective study of color traits is challenged by how to best quantify visual perception in nonhuman species. This requires consideration of at least visual physiology but ultimately also the neural processes underlying perception. Our knowledge of color perception is founded largely on the principles gained from human psychophysics that have proven generalizable based on comparative studies in select animal models. Appreciation of these principles, their empirical foundation, and the reasonable limits to their applicability is crucial to reaching informed conclusions in color research. In this article, we seek a common intellectual basis for the study of color in nature. We first discuss the key perceptual principles, namely, retinal photoreception, sensory channels, opponent processing, color constancy, and receptor noise. We then draw on this basis to inform an analytical framework driven by the research question in relation to identifiable viewers and visual tasks of interest. Consideration of the limits to perceptual inference guides two primary decisions: first, whether a sensory-based approach is necessary and justified and, second, whether the visual task refers to perceptual distance or discriminability. We outline informed approaches in each situation and discuss key challenges for future progress, focusing particularly on how animals perceive color. Given that animal behavior serves as both the basic unit of psychophysics and the ultimate driver of color ecology/evolution, behavioral data are critical to reconciling knowledge across the schools of color research.

The world in color presents a dazzling dimension of phenotypic variation. Biological interest in this variation has burgeoned, due to both increased means for quantifying spectral information and heightened appreciation for how animals view the world differently than humans. Effective study of color traits is challenged by how to best quantify visual perception in nonhuman species. This requires consideration of at least visual physiology but ultimately also the neural processes underlying perception. Our knowledge of color perception is founded largely on the principles gained from human psychophysics that have proven generalizable based on comparative studies in select animal models. Appreciation of these principles, their empirical foundation, and the reasonable limits to their applicability is crucial to reaching informed conclusions in color research. In this article, we seek a common intellectual basis for the study of color in nature. We first discuss the key perceptual principles, namely, retinal photoreception, sensory channels, opponent processing, color constancy, and receptor noise. We then draw on this basis to inform an analytical framework driven by the research question in relation to identifiable viewers and visual tasks of interest. Consideration of the limits to perceptual inference guides two primary decisions: first, whether a sensory-based approach is necessary and justified and, second, whether the visual task refers to perceptual distance or discriminability. We outline informed approaches in each situation and discuss key challenges for future progress, focusing particularly on how animals perceive color. Given that animal behavior serves as both the basic unit of psychophysics and the ultimate driver of color ecology/evolution, behavioral data are critical to reconciling knowledge across the schools of color research.

The world in color presents a dazzling dimension of phenotypic variation. Biological interest in this variation has burgeoned, due to both increased means for quantifying spectral information and heightened appreciation for how animals view the world differently than humans. Effective study of color traits is challenged by how to best quantify visual perception in nonhuman species. This requires consideration of at least visual physiology but ultimately also the neural processes underlying perception. Our knowledge of color perception is founded largely on the principles gained from human psychophysics that have proven generalizable based on comparative studies in select animal models. Appreciation of these principles, their empirical foundation, and the reasonable limits to their applicability is crucial to reaching informed conclusions in color research. In this article, we seek a common intellectual basis for the study of color in nature. We first discuss the key perceptual principles, namely, retinal photoreception, sensory channels, opponent processing, color constancy, and receptor noise. We then draw on this basis to inform an analytical framework driven by the research question in relation to identifiable viewers and visual tasks of interest. Consideration of the limits to perceptual inference guides two primary decisions: first, whether a sensory-based approach is necessary and justified and, second, whether the visual task refers to perceptual distance or discriminability. We outline informed approaches in each situation and discuss key challenges for future progress, focusing particularly on how animals perceive color. Given that animal behavior serves as both the basic unit of psychophysics and the ultimate driver of color ecology/evolution, behavioral data are critical to reconciling knowledge across the schools of color research.

In alpine Australia, Orthoptera are abundant, dominant herbivores, important prey species, and hosts for parasites and parasitoids. Despite the central role of orthopterans in alpine ecosystems, the impact of parasites on orthopteran populations is under-explored. In this study we describe the relationship between parasite prevalence and host sex, body size and year of collection. We accessed an existing, preserved collection of 640 Kosciuscola tristis collected from across its range between 2007 and 2011. Upon dissection we collected juvenile parasites and used molecular tools to identify them to three families (Nematoda; Mermithidae, and Arthropoda: Diptera: Tachinidae and Sarcophagidae). The prevalence of nematodes ranged from 3.5% to 25.0% and dipterans from 2.4% to 20.0%. Contrary to predictions, we found no associations between parasite prevalence and grasshopper sex or size. Although there was an association between prevalence of both nematodes and dipterans with year of collection, this is likely driven by a small sample size in the first year. Our results provide a foundation for future studies into parasite prevalence within the alpine environment and the abiotic factors that might influence these associations.

In alpine Australia, Orthoptera are abundant, dominant herbivores, important prey species, and hosts for parasites and parasitoids. Despite the central role of orthopterans in alpine ecosystems, the impact of parasites on orthopteran populations is under-explored. In this study we describe the relationship between parasite prevalence and host sex, body size and year of collection. We accessed an existing, preserved collection of 640 Kosciuscola tristis collected from across its range between 2007 and 2011. Upon dissection we collected juvenile parasites and used molecular tools to identify them to three families (Nematoda; Mermithidae, and Arthropoda: Diptera: Tachinidae and Sarcophagidae). The prevalence of nematodes ranged from 3.5% to 25.0% and dipterans from 2.4% to 20.0%. Contrary to predictions, we found no associations between parasite prevalence and grasshopper sex or size. Although there was an association between prevalence of both nematodes and dipterans with year of collection, this is likely driven by a small sample size in the first year. Our results provide a foundation for future studies into parasite prevalence within the alpine environment and the abiotic factors that might influence these associations.

The diversity, variability, and apparent rapid evolution of animal genitalia are a vivid focus of research in evolutionary biology, and studies exploring genitalia have dramatically increased over the past decade. These studies, however, exhibit a strong male bias, which has worsened since 2000, despite the fact that this bias has been explicitly pointed out in the past. Early critics argued that previous investigators too often considered only males and their genitalia, while overlooking female genitalia or physiology. Our analysis of the literature shows that overall this male bias has worsened with time. The degree of bias is not consistent between subdisciplines: studies of the lock-and-key hypothesis have been the most male focused, while studies of cryptic female choice usually consider both sexes. The degree of bias also differed across taxonomic groups, but did not associate with the ease of study of male and female genital characteristics. We argue that the persisting male bias in this field cannot solely be explained by anatomical sex differences influencing accessibility. Rather the bias reflects enduring assumptions about the dominant role of males in sex, and invariant female genitalia. New research highlights how rapidly female genital traits can evolve, and how complex coevolutionary dynamics between males and females can shape genital structures. We argue that understanding genital evolution is hampered by an outdated single-sex bias.

The diversity, variability, and apparent rapid evolution of animal genitalia are a vivid focus of research in evolutionary biology, and studies exploring genitalia have dramatically increased over the past decade. These studies, however, exhibit a strong male bias, which has worsened since 2000, despite the fact that this bias has been explicitly pointed out in the past. Early critics argued that previous investigators too often considered only males and their genitalia, while overlooking female genitalia or physiology. Our analysis of the literature shows that overall this male bias has worsened with time. The degree of bias is not consistent between subdisciplines: studies of the lock-and-key hypothesis have been the most male focused, while studies of cryptic female choice usually consider both sexes. The degree of bias also differed across taxonomic groups, but did not associate with the ease of study of male and female genital characteristics. We argue that the persisting male bias in this field cannot solely be explained by anatomical sex differences influencing accessibility. Rather the bias reflects enduring assumptions about the dominant role of males in sex, and invariant female genitalia. New research highlights how rapidly female genital traits can evolve, and how complex coevolutionary dynamics between males and females can shape genital structures. We argue that understanding genital evolution is hampered by an outdated single-sex bias.

The diversity, variability, and apparent rapid evolution of animal genitalia are a vivid focus of research in evolutionary biology, and studies exploring genitalia have dramatically increased over the past decade. These studies, however, exhibit a strong male bias, which has worsened since 2000, despite the fact that this bias has been explicitly pointed out in the past. Early critics argued that previous investigators too often considered only males and their genitalia, while overlooking female genitalia or physiology. Our analysis of the literature shows that overall this male bias has worsened with time. The degree of bias is not consistent between subdisciplines: studies of the lock-and-key hypothesis have been the most male focused, while studies of cryptic female choice usually consider both sexes. The degree of bias also differed across taxonomic groups, but did not associate with the ease of study of male and female genital characteristics. We argue that the persisting male bias in this field cannot solely be explained by anatomical sex differences influencing accessibility. Rather the bias reflects enduring assumptions about the dominant role of males in sex, and invariant female genitalia. New research highlights how rapidly female genital traits can evolve, and how complex coevolutionary dynamics between males and females can shape genital structures. We argue that understanding genital evolution is hampered by an outdated single-sex bias.

The diversity, variability, and apparent rapid evolution of animal genitalia are a vivid focus of research in evolutionary biology, and studies exploring genitalia have dramatically increased over the past decade. These studies, however, exhibit a strong male bias, which has worsened since 2000, despite the fact that this bias has been explicitly pointed out in the past. Early critics argued that previous investigators too often considered only males and their genitalia, while overlooking female genitalia or physiology. Our analysis of the literature shows that overall this male bias has worsened with time. The degree of bias is not consistent between subdisciplines: studies of the lock-and-key hypothesis have been the most male focused, while studies of cryptic female choice usually consider both sexes. The degree of bias also differed across taxonomic groups, but did not associate with the ease of study of male and female genital characteristics. We argue that the persisting male bias in this field cannot solely be explained by anatomical sex differences influencing accessibility. Rather the bias reflects enduring assumptions about the dominant role of males in sex, and invariant female genitalia. New research highlights how rapidly female genital traits can evolve, and how complex coevolutionary dynamics between males and females can shape genital structures. We argue that understanding genital evolution is hampered by an outdated single-sex bias.

The diversity, variability, and apparent rapid evolution of animal genitalia are a vivid focus of research in evolutionary biology, and studies exploring genitalia have dramatically increased over the past decade. These studies, however, exhibit a strong male bias, which has worsened since 2000, despite the fact that this bias has been explicitly pointed out in the past. Early critics argued that previous investigators too often considered only males and their genitalia, while overlooking female genitalia or physiology. Our analysis of the literature shows that overall this male bias has worsened with time. The degree of bias is not consistent between subdisciplines: studies of the lock-and-key hypothesis have been the most male focused, while studies of cryptic female choice usually consider both sexes. The degree of bias also differed across taxonomic groups, but did not associate with the ease of study of male and female genital characteristics. We argue that the persisting male bias in this field cannot solely be explained by anatomical sex differences influencing accessibility. Rather the bias reflects enduring assumptions about the dominant role of males in sex, and invariant female genitalia. New research highlights how rapidly female genital traits can evolve, and how complex coevolutionary dynamics between males and females can shape genital structures. We argue that understanding genital evolution is hampered by an outdated single-sex bias.

The mechanisms and functions of reversible colour change in arthropods are highly diverse despite, or perhaps due to, the presence of an exoskeleton. Physiological colour changes, which have been recorded in 90 arthropod species, are rapid and are the result of changes in the positioning of microstructures or pigments, or in the refractive index of layers in the integument. By contrast, morphological colour changes, documented in 31 species, involve the anabolism or catabolism of components (e.g. pigments) directly related to the observable colour. In this review we highlight the diversity of mechanisms by which reversible colour change occurs and the evolutionary context and diversity of arthropod taxa in which it has been observed. Further, we discuss the functions of reversible colour change so far proposed, review the limited behavioural and ecological data, and argue that the field requires phylogenetically controlled approaches to understanding the evolution of reversible colour change. Finally, we encourage biologists to explore new model systems for colour change and to engage scientists from other disciplines; continued cross-disciplinary collaboration is the most promising approach to this nexus of biology, physics, and chemistry.

The mechanisms and functions of reversible colour change in arthropods are highly diverse despite, or perhaps due to, the presence of an exoskeleton. Physiological colour changes, which have been recorded in 90 arthropod species, are rapid and are the result of changes in the positioning of microstructures or pigments, or in the refractive index of layers in the integument. By contrast, morphological colour changes, documented in 31 species, involve the anabolism or catabolism of components (e.g. pigments) directly related to the observable colour. In this review we highlight the diversity of mechanisms by which reversible colour change occurs and the evolutionary context and diversity of arthropod taxa in which it has been observed. Further, we discuss the functions of reversible colour change so far proposed, review the limited behavioural and ecological data, and argue that the field requires phylogenetically controlled approaches to understanding the evolution of reversible colour change. Finally, we encourage biologists to explore new model systems for colour change and to engage scientists from other disciplines; continued cross-disciplinary collaboration is the most promising approach to this nexus of biology, physics, and chemistry.

Spider orb webs are known to produce colour displays in nature, both in reflection and transmission of sunlight, under certain illumination conditions. The cause of these colours has been the subject of speculation since the time of Newton. It has also been the topic of observational interpretation and some experiment which has proposed diffraction by the fine silks, scattering from rough/structured surfaces and thin film effects as the primary causes. We report systematic studies carried out using the silks of Australian orb web weaving spiders. Studies of both white light and laser light scattering/propagation by natural spider silks have definitively determined the primary cause of the colour displays is rainbows that can be understood by the application of geometric optics combined with new knowledge of the optical properties of the spider web strands, silks, and proteins as optical materials. Additionally, a range of microscopies (optical, AFM, optical surface profiling) show the silks to be optically flat. Overall, spider silks emerge as fascinating optical materials with high dispersion, high birefringence and the potential for future research to show they have high nonlinear optical coefficients. Their importance as a bioinspiration in optics is only just beginning to be realised. Their special optical properties have been achieved by 136 million years of evolution driven by the need for the web to evade detection by insect prey., The original document contains color images. Sponsored in part by Defense Advanced Research Projects Agency. Published in Bioinspiration, Biomimetics, and Bioreplication, the Proceedings of SPIE, v7975, p79750G-1, 2011.